Smoothing round internal passages of additively manufactured parts using metallic spheres

ABSTRACT

A method for smoothing surface roughness within an internal passageway is disclosed. In various embodiments, the method comprises developing a first sphere progression through a length of the internal passageway, each sphere within the first sphere progression having a first sphere diameter greater than or equal to a diameter of the internal passageway; and developing a second sphere progression through the length of the internal passageway, each sphere within the second sphere progression having a second sphere diameter greater than the first sphere diameter, whereby the inner surface of the internal passageway is smoothed, first by the first sphere progression and then by the second sphere progression.

FIELD

The present disclosure relates generally to methods of finishinginternal portions of additively manufactured components and, moreparticularly, to methods in which a series of spheres is used to smoothwalls of circular passageways extending within additively manufacturedcomponents.

BACKGROUND

Fabrication processes such as additive manufacturing enable fabricationof article geometries that are difficult or otherwise impossible to makeby other fabrication techniques. For example, components in gas turbineengines may include internal passages for conveying coolants orlubricants. Additive manufacturing and other advances permit suchpassages to be formed with complex geometries in thin wall structuresand with high-aspect ratios (e.g., the ratio of passage length topassage diametric size). However, due to the additive manufacturingprocess, and even in other fabrication processes, the internal surfacesof these passages can be rough following the fabrication process. Ifleft in the final component, this surface roughness has the potential tointerfere with fluid flow through the passageways.

A technique for smoothing surface roughness or polishing internalsurfaces of conduits or passages in metal components is referred to asballizing, where a machine having a push rod is used to push a sphere ofknown diameter through a machined and generally linear bore hole. Aforce that the sphere exerts on the workpiece as it traverses the lengthof the bore hole shapes and polishes the inner surface of the conduit.Conventional ballizing techniques typically utilize straight bore holesand thus have difficulty smoothing surfaces of conduits or passageshaving curved portions.

SUMMARY

A method for smoothing surface roughness within an internal passagewayis disclosed. In various embodiments, the method comprises the steps ofdetermining a diameter of the internal passageway; urging a first sphereinto the internal passageway and to a first distance along a length ofthe internal passageway, the first sphere having a first sphere diametergreater than or equal to the diameter of the internal passageway; andurging a second sphere into the internal passageway, the second spherehaving a second sphere diameter greater than or equal to the diameter ofthe internal passageway, the second sphere urging the first sphere to asecond distance along the length of the internal passageway, whereby aninner surface of the internal passageway is smoothed by the first spherealong the second distance of the length and the inner surface of theinternal passageway is further smoothed by the second sphere along thefirst distance of the length.

In various embodiments, the method further comprises comprising urging athird sphere into the internal passageway, the third sphere urging thesecond sphere to the second distance along the length of the internalpassageway and the first sphere to a third distance along the internalpassageway. In various embodiments, the method further comprises urgingsubsequent spheres into the internal passageway until the first sphereexits the internal passageway. In various embodiments, the seconddistance is measured from an inlet of the internal passageway. Invarious embodiments, the second distance is measured from a startingpoint within the internal passageway.

In various embodiments, the diameter of the internal passageway is anaverage diameter. In various embodiments, the first sphere diameter isequal to the diameter of the internal passageway. In variousembodiments, the second sphere diameter is equal to the first spherediameter. In various embodiments, the second sphere diameter is greaterthan the first sphere diameter. In various embodiments, the internalpassageway is substantially straight along the length. In variousembodiments, the internal passageway has a curved portion along thelength.

In various embodiments, a set of spheres remaining in the internalpassageway is urged to exit the internal passageway using at least oneof a flexible rod and a source of pressurized air. In variousembodiments, a set of spheres remaining in the passageway is urged toexit the internal passageway using one or more subsequent spheres havinga subsequent sphere diameter less than or equal to the first spherediameter.

A method for smoothing surface roughness within an internal passagewayis disclosed. In various embodiments, the method comprises the steps ofdetermining a diameter of the internal passageway; urging a first sphereinto the internal passageway and to a first distance along a length ofthe internal passageway, the first sphere having a first sphere diametergreater than or equal to the diameter of the internal passageway; andurging a second sphere into the internal passageway, wherein the secondsphere has a second sphere diameter greater than the first spherediameter, the second sphere urging the first sphere to a second distancealong the length of the internal passageway, whereby an inner surface ofthe internal passageway is smoothed by the first sphere along the seconddistance of the length and the inner surface of the internal passagewayis further smoothed along a first portion of the length.

In various embodiments, the method further comprises urging a thirdsphere into the internal passageway, the third sphere urging the secondsphere to the second distance along the length of the internalpassageway and the first sphere to a third distance along the internalpassageway, the third sphere having a third sphere diameter greater thanthe second sphere diameter. In various embodiments, the method furthercomprises urging subsequent spheres into the internal passageway untilthe first sphere exits the internal passageway. In various embodiments,a set of spheres remaining in the internal passageway is urged to exitthe internal passageway using at least one of a rod and a source ofpressurized air.

A method for smoothing surface roughness within an internal passagewayis disclosed. In various embodiments, the method comprises the steps ofdetermining a diameter of the internal passageway; developing a firstsphere progression through a length of the internal passageway, eachmember within the first sphere progression having a first diametergreater than or equal to the diameter of the internal passageway, aninner surface of the internal passageway being smoothed by the firstsphere progression along the length; and developing a second sphereprogression through the length of the internal passageway, each memberwithin the second sphere progression having a second diameter greaterthan the first diameter, the inner surface of the internal passagewaybeing further smoothed by the second sphere progression along thelength.

In various embodiments, the method further comprises developing a finalsphere progression, wherein each member within the final sphereprogression has a final diameter less than a largest sphere diameterassociated with any previous sphere progression developed within theinternal passageway. In various embodiments, the internal passagewayincludes a curved portion.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter of the present disclosure is particularly pointed outand distinctly claimed in the concluding portion of the specification. Amore complete understanding of the present disclosure, however, may bestbe obtained by referring to the following detailed description andclaims in connection with the following drawings. While the drawingsillustrate various embodiments employing the principles describedherein, the drawings do not limit the scope of the claims.

FIG. 1 is a cross sectional schematic view of a gas turbine engine, inaccordance with various embodiments;

FIG. 2 is a cross sectional schematic view of a passageway extendingthrough the interior of an additively manufactured part, in accordancewith various embodiments;

FIGS. 3A, 3B and 3C are cross sectional schematic views of an internalpassageway undergoing a ballizing process, in accordance with variousembodiments;

FIGS. 4A, 4B and 4C are cross sectional schematic views of an internalpassageway undergoing a ballizing process, in accordance with variousembodiments;

FIG. 5 is a cross sectional schematic view of an internal passagewayundergoing a ballizing process, in accordance with various embodiments;and

FIG. 6 is a cross sectional schematic view of an internal passagewayundergoing a ballizing process, in accordance with various embodiments.

DETAILED DESCRIPTION

The following detailed description of various embodiments herein makesreference to the accompanying drawings, which show various embodimentsby way of illustration. While these various embodiments are described insufficient detail to enable those skilled in the art to practice thedisclosure, it should be understood that other embodiments may berealized and that changes may be made without departing from the scopeof the disclosure. Thus, the detailed description herein is presentedfor purposes of illustration only and not of limitation. Furthermore,any reference to singular includes plural embodiments, and any referenceto more than one component or step may include a singular embodiment orstep. Also, any reference to attached, fixed, connected, or the like mayinclude permanent, removable, temporary, partial, full or any otherpossible attachment option. Additionally, any reference to withoutcontact (or similar phrases) may also include reduced contact or minimalcontact. It should also be understood that unless specifically statedotherwise, references to “a,” “an” or “the” may include one or more thanone and that reference to an item in the singular may also include theitem in the plural. Further, all ranges may include upper and lowervalues and all ranges and ratio limits disclosed herein may be combined.

Referring now to the drawings, FIG. 1 schematically illustrates a gasturbine engine 20. The gas turbine engine 20 is disclosed herein as atwo-spool turbofan that generally incorporates a fan section 22, acompressor section 24, a combustor section 26 and a turbine section 28.Alternative engines might include an augmenter section (not shown) amongother systems or features. The fan section 22 drives air along a bypassflow path B in a bypass duct defined within a nacelle 15, while thecompressor section 24 drives air along a primary or core flow path C forcompression and communication into the combustor section 26 and thenexpansion through the turbine section 28. Although depicted as atwo-spool turbofan gas turbine engine in the disclosed non-limitingembodiment, it will be understood that the concepts described herein arenot limited to use with two-spool turbofans as the teachings may beapplied to other types of turbine engines, including three-spoolarchitectures.

The gas turbine engine 20 generally includes a low speed spool 30 and ahigh speed spool 32 mounted for rotation about an engine centrallongitudinal axis A relative to an engine static structure 36 viaseveral bearing systems 38. It should be understood that various bearingsystems at various locations may alternatively or additionally beprovided and the location of the several bearing systems 38 may bevaried as appropriate to the application. The low speed spool 30generally includes an inner shaft 40 that interconnects a fan 42, a lowpressure compressor 44 and a low pressure turbine 46. The inner shaft 40is connected to the fan 42 through a speed change mechanism, which inthis gas turbine engine 20 is illustrated as a fan drive gear system 48configured to drive the fan 42 at a lower speed than the low speed spool30. The high speed spool 32 includes an outer shaft 50 thatinterconnects a high pressure compressor 52 and a high pressure turbine54. A combustor 56 is arranged in the gas turbine engine 20 between thehigh pressure compressor 52 and the high pressure turbine 54. Amid-turbine frame 57 of the engine static structure 36 is arrangedgenerally between the high pressure turbine 54 and the low pressureturbine 46 and may include airfoils 59 in the core flow path C forguiding the flow into the low pressure turbine 46. The mid-turbine frame57 further supports the several bearing systems 38 in the turbinesection 28. The inner shaft 40 and the outer shaft 50 are concentric androtate via the several bearing systems 38 about the engine centrallongitudinal axis A, which is collinear with their longitudinal axes.

The air in the core flow path is compressed by the low pressurecompressor 44 and then the high pressure compressor 52, mixed and burnedwith fuel in the combustor 56, and then expanded over the high pressureturbine 54 and low pressure turbine 46. The low pressure turbine 46 andthe high pressure turbine 54 rotationally drive the respective low speedspool 30 and the high speed spool 32 in response to the expansion. Itwill be appreciated that each of the positions of the fan section 22,the compressor section 24, the combustor section 26, the turbine section28, and the fan drive gear system 48 may be varied. For example, the fandrive gear system 48 may be located aft of the combustor section 26 oreven aft of the turbine section 28, and the fan section 22 may bepositioned forward or aft of the location of the fan drive gear system48.

Various components of the gas turbine engine 20 include conduits orpassageways extending through the component or a portion thereof. Forexample, components in the gas turbine engine 20 may include internalpassageways for conveying a coolant. Such components include, forexample, the blades and the stators that comprise the compressor andturbine sections described above. Such components may also comprisepassageways for conveying bleed air from the compressor to other areasof the gas turbine engine 20 benefitting from a source of high-pressurecooling fluid. Other components comprising conduits or passagewaysinclude the lubrication system, where lubricants are delivered from apump to bearings and the like. Many of these various components areconstructed using additive manufacturing techniques and include conduitsor passageways having curved portions with rough internal surfacesfollowing their manufacture.

Referring now to FIG. 2, a component 200, fabricated through additivemanufacture, is illustrated. The component 200 includes a passageway 202extending from a first end 204 to a second end 206. The passageway 202is defined by an inner surface 208 that, in various embodiments, isgenerally circular in cross section from the first end 204 to the secondend 206. As illustrated, the inner surface 208 of the passageway 202 maybe characterized by an undesirable degree of surface roughness followinginitial fabrication through additive manufacture. In variousembodiments, the passageway 202 is curved at one or more portions alonga length defined by an arc-length distance from the first end 204 to thesecond end 206. As illustrated, for example, the passageway 202, invarious embodiments, includes a first curved portion 210 downstream ofthe first end 204, followed by a substantially straight portion 212, andthen followed by a second curved portion 214 upstream of the second end206. In various embodiments, the first curved portion 210 may becharacterized such that a line of sight does not exist between thelocation of the passageway 202 where the first curved portion 210commences and the location of the passageway 202 where the first curvedportion 210 terminates, or where the substantially straight portion 212commences. A similar characterization applies to the second curvedportion 214 or any additional curved portions that may be present in apassageway. The disclosure that follows provides, among other things, atechnique and method to reduce the surface roughness of the passageway202 within the component 200, or other components having a variousnumbers of curved or straight passageways.

Referring now to FIGS. 3A, 3B and 3C, a series of steps is illustratedwhereby a component 300 undergoes a finishing process following initialfabrication through, for example, additive manufacture. Similar to thecomponent 200 described above with reference to FIG. 2, the component300 includes a passageway 302 having an undesirable degree of surfaceroughness. The passageway 302 extends from a first end 304 to a secondend 306 and is defined by an inner surface 308 that, in variousembodiments, is generally circular in cross section from the first end304 to the second end 306. In various embodiments, the inner surface 308may be defined by a diameter, D, that is the intended diameter of theinner surface 308 or of the passageway 302. In various embodiments, theinner surface 308 may be defined by an average diameter 310, D_(avg),that takes into account the surface roughness along a length of thepassageway 302 or at least a portion thereof. For example, in variousembodiments, the average diameter is the mean between a nominal orintended diameter of the inner surface 308 or the passageway 302 and aminimum diameter—e.g., a diameter that takes into account the peaks ofthe surface roughness extending inward from the inner surface 308. Invarious embodiments, the average diameter is the mean between a maximumdiameter—e.g., a diameter that takes into account the troughs of thesurface roughness extending outward from the inner surface 308—and aminimum diameter—e.g., a diameter that takes into account the peaks ofthe surface roughness extending inward from the inner surface 308.

Referring to FIG. 3A, a first sphere 320 is inserted through the firstend 304 of the passageway 302, followed by a second sphere 322. Thesecond sphere 322 serves to force the first sphere 320 through thepassageway 302 and to further smooth the passageway 302 behind the firstsphere 320. In various embodiments, the first sphere 320 defines anouter surface 324 that is generally spherical in shape and has a firstsphere diameter 326. In various embodiments, the first sphere diameter326 is equal to the average diameter 310 of the passageway 302. As thefirst sphere 320 traverses the passageway 302, the outer surface 324 ofthe first sphere 320 flattens and generally smooths the surfaceroughness present on the inner surface 308 of the passageway 302. As thefirst sphere 320 traverses the passageway 302, the inner surface 308includes a smooth surface 328 that becomes progressively longer alongthe length of the passageway 302 as the first sphere 320 traverses thepassageway 302. Contrarily, as the first sphere 320 traverses thepassageway 302, the inner surface 308 includes a rough surface 330—i.e.,the unsmoothed surface ahead of the first sphere 320—that becomesprogressively shorter as the first sphere 320 traverses the passageway302.

Referring now to FIGS. 3B and 3C, the first sphere 320 is illustratedhaving traversed nearly the entire length of the passageway 302,followed by the second sphere 322. The first sphere 320 and the secondsphere 322 are urged along the length of the passageway 302, from thefirst end 304 to the second end 306, by the introduction of subsequentspheres 340 at the first end 304 of the passageway 302. Each of thesubsequent spheres 340 urges the sphere ahead of it and is itself urgedby the sphere behind it, such that a progression of spheres 350 extendsthrough the passageway 302. As the progression of spheres 350 extendsthrough the passageway 302, the outer surface of each sphere—e.g.,starting with the outer surface 324 of the first sphere320—progressively smooths the rough surface 330 of the inner surface308. As illustrated in FIG. 3C, the first sphere 320 will eventuallyexit the passageway 302 at the second end 306, followed by each of thesubsequent spheres 340. Subsequent spheres 340 are continually added andurged through the passageway 302 until a desired smoothness to the innersurface 308 of the passageway 302 is achieved. Once the desiredsmoothness is achieved, any spheres remaining in the passageway 302 maybe urged toward and through the second end 306 using a flexible rod orhigh pressure air introduced at the first end 304. In variousembodiments, the first sphere begins smoothing starting not from thefirst end 304 or inlet to the passageway 302, but from a starting pointwithin the passageway, such occurring, for example, with passagewayshaving a first portion with a larger diameter than the diameter of asecond portion with a smaller diameter commencing from the startingpoint. In various embodiments, each of the spheres comprises a metalliccomposition having a hardness—e.g., a hardness measured by a Rockwell orBrinell scale—that is harder than the material surrounding thepassageway.

Referring now to FIGS. 4A, 4B and 4C, a series of steps is illustratedwhereby a component 400 undergoes a finishing process following initialfabrication through, for example, additive manufacture. Similar to thecomponent 200 described above with reference to FIG. 2, the component400 includes a passageway 402 having an undesirable degree of surfaceroughness. The passageway 402 extends from a first end 404 to a secondend 406 and is defined by an inner surface 408 that, in variousembodiments, is generally circular in cross section from the first end404 to the second end 406. In various embodiments, the inner surface 408may be defined by an average diameter, D_(avg), that takes into accountthe surface roughness along a length of the passageway 402 or at least aportion thereof.

Referring to FIG. 4A, a first progression of spheres 450 is illustratedextending through the passageway 402. In various embodiments, the firstprogression of spheres 450 starts with the progression of spheres 350discussed above with reference to FIG. 3C. More specifically, theundesired roughness in the passageway 402 may undergo a first smoothingstep by urging a first plurality of spheres through the passageway 402until a desired smoothing is achieved and the first smoothing step iscomplete. As indicated in FIG. 4A, each one of the first plurality ofspheres is identified with the numeral “1.” Each one of the firstplurality of spheres is also defined by a first sphere diameter, D₁.Similar to the discussion above, in various embodiments, the firstsphere diameter D₁ is equal to the average diameter D_(avg) of thepassageway 402 prior to smoothing.

Following completion of the first smoothing step, a second plurality ofspheres is urged through the passageway 402 until a second progressionof spheres 452 is developed, extending from the first end 404 to thesecond end 406 of the passageway 402 or for a portion of the lengththereof. As indicated in FIGS. 4A and 4B, each one of the secondplurality of spheres is identified with the numeral “2.” Each one of thesecond plurality of spheres is also defined by a second sphere diameter,D₂. In various embodiments, the second sphere diameter D₂ is larger thanthe first sphere diameter D₁ by a first diameter difference, ΔD₁=D₂−D₁.The larger second sphere diameter D₂ and, more particularly, the firstdiameter difference ΔD₁ is selected to further smooth the inner surface408 of the passageway 402 until a second smoothing step is complete.

Referring now to FIG. 4C, following completion of the second smoothingstep, a third plurality of spheres is urged through the passageway 402until a third progression of spheres 454 is developed, extending fromthe first end 404 to the second end 406 of the passageway 402 or for aportion of the length thereof. As indicated in FIG. 4C, each one of thethird plurality of spheres is identified with the numeral “3.” Each oneof the third plurality of spheres is also defined by a third spherediameter, D₃. In various embodiments, the third sphere diameter D₃ islarger than the second sphere diameter D₂ by a second diameterdifference, ΔD₂=D₃−D₂. The larger third sphere diameter D₃ and, moreparticularly, the second diameter difference ΔD₂ is selected to yetfurther smooth the inner surface 408 of the passageway 402 until a thirdsmoothing step is complete. In various embodiments, progressively largerspheres may follow the third plurality or progression of spheres toaffect a desired smoothness. In various embodiments, ΔD_(i) (i=1, N) hasa value equal to one (1) to ten (10) microns. In various embodiments,each of the spheres comprises a metallic composition having ahardness—e.g., a hardness measured by a Rockwell or Brinell scale—thatis harder than the material surrounding the passageway.

Referring now to FIG. 5, a process 500 is illustrated whereby acomponent having an internal passageway is fabricated and followed by aseries of steps for smoothing an inner surface of the internalpassageway. According to the process, a component having an internalpassageway is fabricated at a first step 502. In various embodiments,the component is fabricated using an additive manufacturing process.Once the component is fabricated, a first smoothing step 504contemplates developing a first progression of spheres having a firstdiameter, D₁, within the passageway. In various embodiments, the firstsmoothing step 504 is completed and a determination is made whether adesired smoothness within the passageway is achieved 506. If the desiredsmoothness is achieved, the first progression of spheres is removed fromthe passageway and the process 500 is terminated 520.

If the desired smoothing is not achieved, a second smoothing step 508contemplates developing a second progression of spheres having a seconddiameter, D₂, within the passageway. As described above with referenceto FIGS. 4A, 4B and 4C, the second diameter D₂ is larger than the firstdiameter D₁ by a first diameter difference, ΔD₁=D₂−D₁. In variousembodiments, the second smoothing step 508 is completed and adetermination is made whether a desired smoothness within the passagewayis achieved 510. If the desired smoothness is achieved, the secondprogression of spheres is removed from the passageway and the process500 is terminated 520.

If the desired smoothing is not achieved, a third smoothing step 512contemplates developing a third progression of spheres having a thirddiameter, D₃, within the passageway. As described above with referenceto FIGS. 4A, 4B and 4C, the third diameter D₃ is larger than the seconddiameter D₂ by a second diameter difference, ΔD₂=D₃−D₂. In variousembodiments, the third smoothing step 512 is completed and adetermination is made whether a desired smoothness within the passagewayis achieved 514. If the desired smoothness is achieved, the thirdprogression of spheres is removed from the passageway and the process500 is terminated 520. If the desired smoothing is not achieved,subsequent smoothing steps 516 are performed as may be required, usingspheres having progressively larger diameters, D_(i), (i=4, N), untilthe desired smoothness is achieved, at which point the spheres having anNth diameter, D_(N), are removed.

Referring now to FIG. 6, a series of steps is illustrated whereby acomponent 600 undergoes a finishing process following initialfabrication through, for example, additive manufacture. In variousembodiments, the component 600 includes a passageway 602 that may besimilar to the component 200 described above with reference to FIG. 2,including having an undesirable degree of surface roughness. In variousembodiments, the passageway 602 is straight or substantially straight,such that the passageway includes no curves along its length. Thepassageway 602 extends from a first end 604 to a second end 606 and isdefined by an inner surface 608 that, in various embodiments, isgenerally circular in cross section from the first end 604 to the secondend 606. In various embodiments, the inner surface 608 may be defined byan average diameter 610, prior to smoothing, that takes into account thesurface roughness along a length of the passageway 602 or at least aportion thereof.

In various embodiments, a first ball, identified with the numeral “1,”is inserted into the passageway 602 at the first end 604, followedsequentially by a second ball, identified with the numeral “2,” a thirdball, identified with the numeral “3,” and a fourth ball, identifiedwith the numeral “4.” Each sphere has a progressively larger diameter,such that D₄>D₃>D₂>D₁. Subsequent spheres, having progressively largerdiameters, D_(i), (i=5, N) may follow, as may be required. In variousembodiments, the progression of spheres having progressively largerdiameters D_(i) (i=1,N) is used to smooth the inner surface 608 until adesired smoothness is achieved. In various embodiments, where thematerial comprising the component 600 is sufficiently soft, theprogression of spheres having progressively larger diameters D_(i)(i=1,N) may also be used to enlarge the diameter of the passageway 602from the average diameter 610 following initial fabrication of thecomponent 600 to a final diameter 614. In various embodiments, followingthe final sphere being inserted—e.g., Sphere 4 having diameter D₄—a rod612 may be employed to urge the final sphere and any preceding spheresremaining within the passageway 602 out the second end 606 of thepassageway 602. In various embodiments, progressively larger spheres mayfollow to affect a desired smoothness or enlargement. In variousembodiments, the difference between sphere diameters has a value equalto one (1) to ten (10) microns. In various embodiments, each of thespheres comprises a metallic composition having a hardness—e.g., ahardness measured by a Rockwell or Brinell scale—that is harder than thematerial surrounding the passageway.

In various embodiments, a source 616 of high pressure air may also beused to urge the spheres remaining in the passageway 602 out the secondend 606. In various embodiments, the rod 612, which may be a flexiblerod capable of negotiating curved passageways, or the source 616 of highpressure air, may be used with any of the other embodiments describedabove to remove one or more spheres remaining in a passageway—e.g., thepassageway 302 referred to above with reference to FIGS. 3A, 3B and 3Cor the passageway 402 referred to above with reference to FIGS. 4A, 4Band 4C—following smoothing or diameter increasing processes. In variousembodiments, spheres having smaller diameters than the spheres remainingin a straight or curved passageway may be used to urge any spheresremaining in the passageway out an exit portion of the passageway.

Finally, it should be understood that any of the above describedconcepts can be used alone or in combination with any or all of theother above described concepts. Although various embodiments have beendisclosed and described, one of ordinary skill in this art wouldrecognize that certain modifications would come within the scope of thisdisclosure. Accordingly, the description is not intended to beexhaustive or to limit the principles described or illustrated herein toany precise form. Many modifications and variations are possible inlight of the above teaching.

Benefits, other advantages, and solutions to problems have beendescribed herein with regard to specific embodiments. Furthermore, theconnecting lines shown in the various figures contained herein areintended to represent exemplary functional relationships and/or physicalcouplings between the various elements. It should be noted that manyalternative or additional functional relationships or physicalconnections may be present in a practical system. However, the benefits,advantages, solutions to problems, and any elements that may cause anybenefit, advantage, or solution to occur or become more pronounced arenot to be construed as critical, required, or essential features orelements of the disclosure. The scope of the disclosure is accordinglyto be limited by nothing other than the appended claims, in whichreference to an element in the singular is not intended to mean “one andonly one” unless explicitly so stated, but rather “one or more.”Moreover, where a phrase similar to “at least one of A, B, or C” is usedin the claims, it is intended that the phrase be interpreted to meanthat A alone may be present in an embodiment, B alone may be present inan embodiment, C alone may be present in an embodiment, or that anycombination of the elements A, B and C may be present in a singleembodiment; for example, A and B, A and C, B and C, or A and B and C.Different cross-hatching is used throughout the figures to denotedifferent parts but not necessarily to denote the same or differentmaterials.

Systems, methods and apparatus are provided herein. In the detaileddescription herein, references to “one embodiment”, “an embodiment”,“various embodiments”, etc., indicate that the embodiment described mayinclude a particular feature, structure, or characteristic, but everyembodiment may not necessarily include the particular feature,structure, or characteristic. Moreover, such phrases are not necessarilyreferring to the same embodiment. Further, when a particular feature,structure, or characteristic is described in connection with anembodiment, it is submitted that it is within the knowledge of oneskilled in the art to affect such feature, structure, or characteristicin connection with other embodiments whether or not explicitlydescribed. After reading the description, it will be apparent to oneskilled in the relevant art(s) how to implement the disclosure inalternative embodiments.

Furthermore, no element, component, or method step in the presentdisclosure is intended to be dedicated to the public regardless ofwhether the element, component, or method step is explicitly recited inthe claims. No claim element herein is to be construed under theprovisions of 35 U.S.C. 112(f) unless the element is expressly recitedusing the phrase “means for.” As used herein, the terms “comprises”,“comprising”, or any other variation thereof, are intended to cover anon-exclusive inclusion, such that a process, method, article, orapparatus that comprises a list of elements does not include only thoseelements but may include other elements not expressly listed or inherentto such process, method, article, or apparatus.

What is claimed is:
 1. A method for smoothing surface roughness withinan internal passageway, comprising: urging a first sphere into theinternal passageway and to a first distance along a first curved portionof a length of the internal passageway, wherein the first sphere has afirst sphere diameter greater than or equal to a diameter of theinternal passageway; urging a second sphere into the internalpassageway, the second sphere having a second sphere diameter greaterthan or equal to the diameter of the internal passageway, the secondsphere urging the first sphere to a second distance along the firstcurved portion of the length of the internal passageway; urging thefirst sphere along a substantially straight portion of the internalpassageway downstream of the first curved portion via the second sphere;and urging the first sphere along a second curved portion of theinternal passageway downstream of the substantially straight portion viathe second sphere, wherein an inner surface of the internal passagewayis smoothed by the first sphere along the second distance of the lengthand wherein the inner surface of the internal passageway is furthersmoothed by the second sphere along the first distance of the length andwherein the first curved portion, the substantially straight portion andthe second curved portion extend along an arc-length distance of thelength of the internal passageway.
 2. The method of claim 1, furthercomprising urging a third sphere into the internal passageway, the thirdsphere urging the second sphere to the second distance along the lengthof the internal passageway and the first sphere to a third distancealong the internal passageway.
 3. The method of claim 2, furthercomprising urging subsequent spheres into the internal passageway untilthe first sphere exits the internal passageway.
 4. The method of claim1, wherein the second distance is measured from an inlet of the internalpassageway.
 5. The method of claim 1, wherein the second distance ismeasured from a starting point within the internal passageway.
 6. Themethod of claim 1, wherein the diameter of the internal passageway is anaverage diameter.
 7. The method of claim 1, wherein the first spherediameter is equal to the diameter of the internal passageway.
 8. Themethod of claim 1, wherein the second sphere diameter is equal to thefirst sphere diameter.
 9. The method of claim 1, wherein the secondsphere diameter is greater than the first sphere diameter.